Variable-pitch propeller



NOV. 18, 1930. c GREENE 1,782,167

VARIABLE PITCH PROPELLER I Filed Nov. 20, 1928 2 Sheets-Sheet l 39V 8 I8 I. J a 5 I 40 L 3 1B /9 l- 3? 5 Z7 26 i I N VEN TOR.

A TTORNE YS.

20, 1928 2 Sheets-Shgt 2 I INVENTOR.

Clare/1c Jfir/r drag/1e.

B H? ATTORNEYS.

C. K. GREENE VARIABLE PITCH PROPELLER Filed Nov.

Nov. 18, 1930.

IIIIIIIIIIIJ- n [hr/II Patented Nov.. 18, 1930 UNITED STATES CLARENCEKIRK GREENE, OF CANANEA, MEXICO VARIABLE-PITCH PROPELLER Applicationfiled November'20, 1928. Serial No. 320,640.

My invention relates generally to propellers, and it is a purpose of myinvention to provide a propeller having blades adjustable to vary thethrust exerted thereby when the propeller is in operation, and hencevary the propelling force exerted by the propeller.

It is a further purpose of my invention to provide a propeller of theabove described character, particularly adapted, although notnecessarily, for aircraft use, and capable of being readily adjustedwhen in operation, to vary the angle of incidence of its blades to suchextent that either forward or rearward propelling forces varying from aminia mum to a maximum in either direction can be obtained from theblades, to the end that by suitable adjustment of the blades, maximumefficiency can be obtained from the propeller regardless of variationsin atmospheric conditions, variations in the gradient at which the craftis traveling, and variations in load carried b the craft, as well asproviding an effective rake for checking the speed of the craft whenlanding so that the craft can be brought to a standstill in a relativelyshort distance of travel.

I will describe only one form of variable pitch propeller embodying myinvention, and will then point out the novel features thereof in claims.

In the accompanying drawings- Fig. 1 is a view showing in, plan the forward end of a conventional heavier-than-air craft with one form ofvariable pitch propel-' ler embodying my invention applied thereto; Fig.2 is a View in front elevation of the variable pitch propeller shown inFig. 1, with the blades of the propeller broken away;

Fig. 3 is a view of the variable pitch propeller in side elevation;

Fig. 4 is a. vertlcal sectional view taken on the line 44 of Fig. 3 andlooking inthe direction of the arrows;

Fig. 5'is a vertical sectional View taken on the line 5-5 of Fig. 4 andlooking in the direction of the arrows;

Fig. 6 is a horizontal sectional view taken onthe line 6-6 of Fig. 2 andlooking in the direction of the arrows; and

to Fig. 7 is a fragmentary detail sectional view taken on the line 77 ofFig. 2 and looking in the direction of the arrows.

Referring specifically to the drawings in which similar referencecharacters designate similar parts in each of the several views, myinvention in its present embodiment comprises a propeller designatedgenerally at P and including a hub 10 in the form of an elongated sleevebored transversely medially between its ends to receive a shaft 11,which in a direct drive installation constitutes the crankshaft of apower plant K of an aircraft. The hub 10 is fixed to the shaft 11 so asto be rotated thereby, by means of a key 12, and is retained againstdisplacement from the shaft by means of a nut 13 threaded on the shaftand co-operating with an annular shoulder 14 formed on the shaft toclamp the hub on the latter. j

J ournaled in the opposite ends of the hub 10 are a pair of stub shafts15 and 16 to which are fixedly secured in any suitable manner blades Band B respectively of conventional form. The blades B and B are thusrotatably mounted in the hub 10 so that the angles of incidences orpitch of the blades, and hence the thrustexerted by the blades when thepropeller is in operation, can be varied.

The shafts 15 and 16 and hence the blades B and B are adapted to berotated in opposed directions, and to this end a fixed support S in theform of a frame is rigidly se cured to the aircraft in any suitablemanner, and is provided with a central hub 17 in which is journaled thepropeller shaft 11 at a point rearwa-rdly of the propeller P. Projectingfrom the central hub 17 in opposed directions are arms 18 and 19-havingsleeves 20. and 21 respectively in which are journaled stub shafts 22and 23 respectively, disposed parallel to and at opposite sides of thepropeller shaft 11. The shafts 22 and 23 project from opposite ends oftheir respective sleeves 20 and 21 and to the projecting ends of theshaft 22, a pair of idler gears 24 and 25 are fixed, while to theprojecting ends of the shaft 23, a second pair of idler gears 26 and 27are fixed.

1 The idler gears 25 and 27 constantly mesh with a single driven gear 28which is fixed to or formed integral with a relatively large gear 29.The driven gear 28 and the gear 29 are rotatably mounted on thepropeller shaft 11, and to insure that these gears normally will rotatewith the shaft yet can be rotated independently of the shaft, a spring30 surrounds the shaft and bears against the driven gear 28 to urge thelatter and the gear 29 towards the propeller hub 10 and maintain thegear 29 in engagement with suitable projections 31 on the hub.

The gear 29 constantly meshes with a pair of driven pinions 32 and 33fixed to shafts 34 and 35 respectively, rotatably mounted respectivelyin brackets 36 and 37 secured to the hub 10. Also fixed to the shafts 34and 35 are worms 38 and 39 respectively, constantly meshing with wormwheels 40 and 41 respectively, fixed to the stub shafts 15 and 16respectively, of the propeller P.

Fixed to the propeller shaft 11 at the rear of the support S and in theplane of the idler gears 24 and 26 is a driving gear 42 which is adaptedto be operatively connected with either the idler gear 24 or the idlergear 26. To this end an arm 43 is mounted on the propeller shaft 11 atthe rear of the driving gear 42, for rocking movement, and carries apinion 44 constantly meshing with the driving gear 42, and a gear 45constantly meshing with the pinion 44. The gear 45 is adapted to bebrought into mesh with either the idler gear 24 or the idler gear 26 tocause one or the other of the latter gears to be driven in the oppositedirection to the propeller shaft by the driving gear 42, according asthe arm 43 is shifted from an inactive position shown in Fig. 2 toeither the active position shown in full lines in Fig. 4 or the activeposition shown in broken lines in this figure; and to permit manualoperation of the arm 43 by the pilot, any suitable control may beprovided. For the purpose of illustration a form of control is shown andcom-.

prises flexible cables 46 and 47 connected at one of their ends to anextension 48 of the arm 43, and then trained over sheaves 49, 49 and 50,50 for connection at their other ends to an operating lever 51 .pivotedat 52 in the cockpit of the aircraft in advance of the pilots seat, tothe end that rocking movement of the lever 51 will effect correspondingrocking movement of the arm 43.

The operation of the propeller is as follows:

With the arm 43 occupying the inactive position shown in Fig. 2, andassuming that the shaft 11 is rotating in a counter-clockwise directionas indicated by the arrow in this figure, the gears 28 and 29 willrotate with the shaft 11 and at the same speed as the latter due to thefriction set up by the spring 30,

, the pairs of idler gears 24, 25 and 26, 27 being driven idly by thegear 28, and the pinion 44 and gear 45 being driven idly 'by the drivinggear 42. As the worm wheels 40, 41, worms 38, 39, and pinions 32, 33rotate bodily with the propeller P, there will be no relative movementbetween the gear 29 and the pinions 32 and 33 so that the angles ofincidences of the blades B and B will remain constant. Furthermore itwill be clearly evident that the air pressure acting against the bladeswill be inefiective to change their incidence angles due to the factthat the worm wheels 40 and 41 cannot drive their respective worms 38and 39 so that the blades are locked in a selected postion ofadjustment.

However, when the arm 43 is rocked to the position shown in full linesin Fig. 4 by proper manipulation of the operating lever 51, the gear 45on the arm 43 will be brought into mesh With the idler gear 24, so thatthe latter will be positively driven from the driving gear 42 in acounter-clockwise direction as viewed in Fig. 4, the ratios between thelatter gear and' the pinion 44, gear 45, idler gears 24 and 25, anddriven gear 28 being such as to cause the driven gear 28 to bepositively driven in the same direction as and at a speed slightly inexcess of the speed of the propeller shaft 11, thus causing-the gear 29to drive the pinion gears 32 and 33, and hence drive the worms 38, 39and worm wheels 40, 41 to rotate the stub shafts 15 and 16 and therebyvary the angles of incidences of the blades B and B in one direction.

When the desired adjustment of'the propeller blades has been effected,the arm 43 is again moved to its inactive position.

Upon rocking the arm 43 to the position shown in broken lines in Fig. 4,the gear 45 will be brought into mesh with the idler gear 26 whichlatter, it will be noted, is slightly larger than the idler gear 24.With a given propeller shaft speed the idler gear 26 will be driven at asufficiently slower speed than would the idler gear 24, to cause thedriven gear 28 to be positively driven in the same direction as, and ata speed slightly less than the speed of the propeller shaft 11, thuscausing the pinion gears 32, 33, worms 38, 39, and worm wheels 40 and 41to be driven ina direction reverse to that in which they were previouslydriven when the idler gear 24 was being driven from the driving ear 28,thus reversely rotating the stub sha ts 15 and 16 and hence varying theangles of incidences of the blades B and B in the reverse direction.

It will thus be clear that the incidence angles of the blades B and Bcan be varied to cause the blades to exert thrust from a minimum to amaximum in either a forward or rearward direction, all while thepropeller is in operation and under perfect control of theoperator, sothat maximum efficiency can be obtained from the blades under variedflying conditions, and that the blades when adjusted to exert a forwardthrust-produce an effective brake for the aircraft by which the Ill)latter, when landing, can be brought to rest in a relatively shortdistance of travel.

It will be manifest that broadly speaking the worm wheels 40, 41, worms38, 39, and pinions 32 and 33 constitute a means for moving the blades Band B to vary their incidence angles; that the gears 28 and 29 broadlyconstitute rotatable means and the gear 28 a rotatable member fordriving the blades moving means to cause the incidence angles of theblades to be varied, when the rotatable member is driven ataspeeddifferent than the propeller speed, and more specifically to cause theincidence angles of the blades to be varied in one direction or thereverse direction according as the rotatable member is driven ata speedin excess of or .less than the propeller speed. Furthermore,

it will be understood that the two pairs of idler gears 24, 25 and 26,27 respectively broadly constitute two means, one for driving therotatable member (the gear 28) at a speed in excess of the propellerspeed, and the other for driving the rotatable member at a speed lessthan the propeller speed; that the driving gear 42 broadly constitutes adriving means for the above two means; and that the pinion 44 and gear45 broadly constitute a means for operatively connecting the drivingmeans to either of the above mentioned two means independently of theother.

Although I have herein shown and described only one form of variablepitch propeller embodying my invention, it is to be understood thatvarious changes and modifications may be made herein without departingfrom the spirit of the invention and the spirit and scope of theappended claims.

I claim: I

1. A rotary propeller having blades adjustable to vary the angles ofincidences thereof, means including a gear rotatably mounted on thepropeller shaft, for moving 'the blades to vary their angles ofincidences in response to driving of said gear at a speed different fromthe propeller speed, means for driving said gear at a speed differentfrom the propeller speed including a driving gear fixed to the propellershaft, and means for operatively connecting the driving gear to anddisconnecting it from the first mentioned ear.

D 2; A rotary propeller having blades adjust-able to vary the angles ofincidences thereof, means including a gear rotatably mounted on thepropeller shaft, for moving the blades to vary their angles ofincidences in response to driving of said gear at a speed different fromthe propeller speed, a pair of idler gears mounted for rotation as aunit about a fixed axis and one of which constantly meshes with saidgear, a driving gear fixed to the propeller shaft, and means foroperatively connecting the driving gear tov the 3.- A rotary propellerhaving blades adjustable to vary the angles of incidences thereof, meansincluding a ear rotatably mounted on the propeller sha t, for moving theblades to vary their angles of incidences in response to driving of sa1dgear at a speed different from the propeller speed, a pair of idlergears mounted for rotation as a unit about a fixed axis'and one of whichconstantly meshes with said gear, a driving gear fixed to the propellershaft, and means for operatively connecting the driving gear to theother of the pair of idler gears to cause said one of the latter torotate the first mentioned gear at a speed different from the rotationalspeed of the propeller, said last means comprising a gear constantlydriven by the driving gear, and mounted for movement bodily to oneposition wherein it meshes with the other of said pair of idler gears,and to another position wherein it is out of mesh with the other of saidpair of idler gears. I

4. A rotary propeller having blades adjustable to vary the angles ofincidences thereof, means including a gear rotatablymounted on thepropeller shaft, for moving the blades to vary their angles ofincidences in response to driving of said gear at a speed different fromthe propeller speed, a pair of idler gears mounted for rotation as aunit about a fixed axis and one of which constantly meshes with saidgear, a driving gear fixed to the propeller shaft, and means foroperatively connecting the driving gear to the other of the pair ofidler gears to cause said one of the latter to rotate the firstmentioned gear at a speed different from the rotational speed of thepropeller, said last means comprising an arm mounted on the propellershaft for rocking movement and having a pinion constantly meshing withthe driving gear, and a gear mounted on the arm, constantly meshing withthe pinion and adapted to be brought into or out of mesh with the otherof the pair of idler gears according as the arm is rocked to oneposition or another.

5. A rotary propeller having blades adjustable to vary the angles ofincidences thereof, means, including a gear rotatably mounted on thepropeller shaft, for moving the blades to vary their angles ofincidences in one direction or the reverse direction. according as saidgear is driven at a speed in excess of the propeller speed or at a speedless than the propeller speed, two gear means, one for driving said gearat a speed in excess of the propeller speed and the other for drivingsaid gear at a speed less than the propeller speed, a driving 'gearfixed to the propeller shaft, and means for operatively connecting thedriving gear to either of the two gear means independently of the other.

6. A rotary propeller having blades adjustable to vary their angles ofincidences, means including a rotatable member for moving the blades tovary their angles of incidences in one direction or the reversedirection, according as the rotatable member is driven at a speed inexcess of the propeller speed or at a speed less than the propellerspeed, two means, one for driving the rotatable member in one directionand at a speed in excess of the propeller speed and the other fordriving the rotatable member in said one direction and at a speed lessthan the propeller speed, driving means for said two means, and meansfor operatively connecting the driving means to either of said two meansindependently of the other.

7. A rotary propeller having blades adj ustable to vary their angles ofincidences, means including a gear rotatabl mounted on the propellershaft, for moving the blades to vary their angles of incidences in onedirection or the reverse direction, according as said gear is driven ata speed in excess of the propeller speed or at a speed less than thepropeller speed, two means, one for driving said gear in one directionand at a speed in excess of the propeller speed and the other fordriving said ear in said one direction and at a speed less than thepropeller speed, driving means for said two means comprising a gearfixed to the propeller shaft, and means for operatively connecting thedriving gear to either of said two means independently of the other.

8. A rotary propeller having blades adj ustable to vary their angles ofincidences, means including a gear rotatably mounted on the propellershaft, for moving the .blades to vary their angles of incidences in onedirection or the reverse direction, according as said gear is driven ata speed in excess of the propeller speed or at a speed less than thepropeller speed, two means, one for driving said gear at a speed inexcess of the propeller speed and the other. for drivmg said gear at aspeed less than the propeller speed, driving means for said two meanscomprising a gear fixed to the propeller shaft, and means foroperatively connecting the driving gear to either of said two meansindependently of the other, said two means comprising two pairs of idlergears of respectively different ratios with each pair mounted forrotation as a unit about a fixed axis and one gear of each pairconstantly meshing with the first mentioned gear.

9. A rotary propeller having blades adj ustable to vary their angles ofincidences, means including a gear rotatably mounted on the propellershaft, for moving the blades to vary their angles ofincidences in onedirection or the reverse direction, according as said gear is driven ata speed in excess of the propeller speed or at a speed less than thepropeller speed, two means, one for driving said gear at a speed inexcess of the propeller speed and the other for driving said gear at aspeed less than the propeller speed, driving means for said two meanscomprising a gear fixed to the propeller shaft, and means foroperatively connecting the driving gear to either of said two meansindependently of the'other, said two means comprising two pairs of idlergears of respectively different ratios with each pair mounted forrotation as a unit about a fixed axis and one gear of each pair,constantly meshing with the first mentioned gear, and said means foroperatively connecting the driving gear to either of the two meanscomprising a gear constantly driven from the driving gear and mountedfor movement bodily to one position wherein it meshes with the other ofone of said pairs of idler gears, a second osition wherein it mesheswith the other 0 the other of said pairs of idler gears, and a thirdposition wherein it is out of mesh with both of the others of the pairsof idler gears.

10. A rotatably mounted propeller comprising a hub, stub shaftsrotatably mounted in the hub, blades fixed to the stub shafts,

by cause the angles of incidences of the blades to be varied in onedirection or the reverse direction, according as the rotatable memher isdriven at a speed in excess of the propeller speed or driven at a speedless than the propeller speed, two means, one for driving the rotatablemember in one direction and at a speed in excess of the propeller speedand the other for driving the rotatable member in said one direction andat a speed less than the propeller speed, driving means for said twomeans, and means for operatively connecting the driving means to eitherof said two means independently of the other.

11. A rotatably mounted propeller comprising a hub, stub shaftsrotatably mounted in the hub, blades fixed to the stub shafts, wormwheels fixed to the shafts, worms eonstantly meshing with the wormwheels, means, including a gear rotatably mounted on the propeller shaftfor driving the'worms in one direction or the other and thereby causethe angles of incidences of the blades to be varied in one direction orthe reverse direction according as said gear is driven at a speed 1nexcess of the propeller speed or drlven at a speed less than thepropeller speed, two means, one for driving said ear in one directionand at a speed in excess 0 the propeller speed and the other for drivingsaid gear in said one direction and at a speed less than the propellerspeed, driving means for said two means comprising a gear fixed to thepropell'er'shaft, and means for operatively connecting the driving gearto either of said two means independently of the other.

Signed at Naco in the county of Cochise and State of Arizona this, 6thday of November, A. D. 1928.

CLARENCE KIRK GREENE.

